Multi-cell rechargeable batteries are utilized in many applications because of their relatively high capacity. Such applications include, but are not limited to, electronic devices such as laptops, cellular phones, personal digital assistants, and the like. Certain types of battery packs, e.g., a Lithium ion (Li-ion) battery, can provide various power supply voltages adapted for various power voltage applications by using battery cells of different cell numbers. For example, a Li-ion battery can be used to provide different voltages in many power supply applications, such as 10.8 V (by using 3 cells), 14.4 V (by using 4 cells), 18 V (by using 5 cells), and 21.6 V (by using 6 cells), etc. As such, a battery management integrated circuit (IC) for monitoring and protecting the battery pack need to be configured properly to support the battery pack of different cell numbers.
Some traditional methods to configure the battery management IC include one time programmable (OTP) configuration, microprocessor control unit (MCU) configuration, and additional pin configuration. Referring to FIG. 1, a battery management IC 102 in accordance with the conventional OTP configuration is illustrated. The battery management IC 102 is integrated with an OTP memory 104. Usually, automated test equipment 106 configures the OTP memory 104 during a chip testing period so as to make the battery management IC 102 support a specific battery cell number. However, after the configuration, the battery management IC 102 may not support the batteries having other cell numbers.
Referring to FIG. 2, a battery management IC 202 in accordance with the conventional MCU configuration is illustrated. Information of the battery cell number is stored in a MCU 206 which configures a register 204 in the battery management IC 202. When the battery management IC 202 powers on, the cell number information is written into the register 204 by the MCU 206. The battery management IC 202 can support more different cell numbers, but the MCU 206 requires software and the cost is relatively expensive.
Referring to FIG. 3, a battery management IC 302 in accordance with the conventional additional pin configuration is illustrated. Several pins of the battery management IC 302 are used for configuring the battery management IC 302. In FIG. 3, the battery management IC 302 includes two configuration pins 304 and 306, which can be tied to different voltage levels, to indicate the cell numbers supported by the battery management IC 302. For example, when the configuration pin 304 is tied to a source voltage (VDD) and the configuration pin 306 is tied to a ground voltage (VSS), the supported cell number is, e.g., 5. When the configuration pins 304 and 306 are both tied to VSS, the cell number is 3; when the pins 304 and 306 are both tied to VDD, the cell number is 6. However, in order to support different numbers of battery cells, layout of the printed circuit board (PCB, not shown in FIG. 3), which the battery management IC 302 is fixed onto, needs to be modified to tie configuration pins 304 and 306 to different voltage levels.